Controlling the Tensile Strength of Gray and Ductile Iron


For the latter stages of my career, I’ve focused a great deal of my attention to controlling the tensile strength of gray and ductile iron. It’s been an interesting journey for a number of reasons. One of the aspects making it interesting was what is in the literature. I found two serious problems with what was in the literature. The first of the problems was finding information in the literature. Finding articles about controlling the strength of iron was impossible and much of what was written was tucked in articles mainly dealing with some other aspect of iron metallurgy. The few articles written primarily about tensile testing were about some specific aspect of the process. I couldn’t find any articles dealing with the overall process of controlling the strength.


The other serious problem I found was that much of what was in the literature came from research settings. It’s been my experience that information gathered from small furnaces in a research setting does not always correlate to what I experienced in production settings with larger furnaces.


As my career is drawing to its close, I thought I’d try to compile what I’ve learned about controlling the tensile strength of gray and ductile into one place. Rather than waiting to make the information available as one grand endeavor, my plan is to do that in a series of essays that will be updated and revised as I feel inspired or find the need. The following outline is what is planned. If there is not a “completed on” or “revised on” following the subject it means I haven’t be inspired enough to complete that section yet. Of course, to get to completed sections, click on the hyperlinked title.


As always, I always welcome comments and/or suggestions.


1.                  Why tensile testing

2.                  What is a tensile test

3.                  What is control

            a.    Current Control of Gray Iron Tensile Properties  As reported in “web only” Modern Casting article in July 2002 relates the results of a survey taken by the Cast Iron Quality Control Control Committee. (I have found another version of this with the data shown differently, I'm not sure if it was published or not, but it be worth reading if you're interested. Bench Marking Iron Control )

            b.     What is good control Completed on 2/8/2010

4.                  What controls tensile strength in iron

a.      Cooling rate - "Effect of Cooling Rate on Ductile Iron Mechanical    Properties" - Published in the 2002 AFS Transactions

b.      Nucleation

c.      Chemistry - "Effect of Elements in Gray & Ductile Iron" (12-20-2008)


     5.      How to Screw Up a Tensile Test Completed 2/5/18

       6.          Figuring out why tensile tests fail Completed On 2/8/2009

7.     I developed a test for non-technical types to determine their understanding of iron titled:

 How Good Is Your Basic Iron Metallurgy?  (Completed On 3/31/2015)